Phase Composition, Density, and Ionic Conductivity of the Li7La3Zr2O12-Based Composites with LiPO3 Glass Addition

The glass-ceramic composite electrolytes based on tetragonal Li 7 La 3 Zr 2 O 12 (t-LLZ) and cubic Al-doped Li 7 La 3 Zr 2 O 12 (c-LLZ) with the LiPO 3 glass additive have been prepared. The electrical conductivity and microstructure of the t-LLZ/LiPO 3 and c-LLZ/LiPO 3 composites have been investigated. The phase evolution of electrolytes has been studied using XRD, SEM, and Raman spectroscopy. It was indicated that the impurities formation depends on the composition of the composite. The phase composition of the solid electrolytes determines their thermal properties, which have been studied by the DSC method. The relative density of the obtained composite electrolytes was established to be higher than one of the sintered t-LLZ and c-LLZ. The Li + conductivity of the t-LLZ-based composites gradually increased from 4.6 × 10 –7 S cm –1 (undoped t-LLZ) to 2.5 × 10 –6 S cm –1 (t-LLZ/5 wt % LiPO 3 composite) at 25 °C. The highest total conductivity of the c-LLZ/LiPO 3 composites has been achieved by introducing 1 wt % additive (0.11 mS cm –1 at room temperature), whereas further doping resulted in the impurities formation.